The invention relates to a hybrid drive, in particular for motor vehicles.
Accordingly, the invention relates to a hybrid drive, in particular for motor vehicles, containing a power-output shaft of a propulsion drive engine; a transmission input shaft arranged axially with respect to the engine power-output shaft; an engageable clutch, which is arranged coaxially with the rotational center line of the engine shaft and the transmission power-input shaft for the purpose of connecting the two shafts in a torque-transmitting manner; a first electric machine, which has a stator and a rotor that is connected or can be connected to the engine power-output shaft in a torque-transmitting manner.
DE 199 05 366 C2 discloses a hybrid drive. It shows a crankshaft of a combustion engine, which can be connected in a torque-transmitting manner, by a clutch, to a transmission input shaft arranged axially with respect to it. A torsional vibration damper is arranged in the connection between the crankshaft and the primary part of the clutch. The single electric machine is an internal-rotor machine (rotor radially inside a stator). The rotor of the electric machine is connected to the crankshaft in a torque-transmitting manner, ahead of the torsional vibration damper in terms of the direction of power transmission of the propulsion drive engine.
DE 41 24 479 A1 discloses a hybrid drive in which an engine power-output shaft of a propulsion drive engine is connected in a torque-transmitting manner via a planetary transmission to a transmission power-output shaft arranged axially relative to the planetary transmission. The rotor of a second electric machine, which is arranged coaxially to the transmission power-output shaft, is furthermore likewise connected in a torque-transmitting manner to the transmission power-output shaft via the planetary transmission. The planetary transmission can be locked up by means of an engageable clutch. Both electric machines are internal-rotor machines, which have a rotor arranged within a stator.
The prior art also includes a hybrid concept, which is illustrated in FIG. 4. In this concept, the crankshaft of a combustion engine (VM) is connected to an intermediate shaft via a torsional vibration damper (TD). The intermediate shaft is provided with two clutches (K1, K2). A first electric machine (EM1) and a pump (P) can be connected by means of one clutch (K1), and a transmission input shaft of an automatic transmission (AT) can be connected by means of the second clutch (K2). A second electric machine (EM2) is connected to the transmission input shaft in a torque-transmitting manner. This hybrid concept is shown on page 635 of a book entitled “VDI Berichte” [VDI Reports] published in 2000.
The invention is intended to construct a hybrid drive in such a way that it requires less installation space while providing at least the same drive transmission power.
The reduction in installation space should preferably be such that at least two electric machines, a clutch between two shafts arranged axially with respect to one another, and preferably also a torsional vibration damper can be accommodated in a case, in particular a case bell. This case has previously been used to accommodate a torque converter for an automatic transmission, which can be driven by the transmission power-input shaft, preferably by the transmission input shaft itself. The engine power-output shaft is preferably the crankshaft of a combustion engine or a shaft that is connected or can be connected in a torque-transmitting manner to the crankshaft.
The invention preferably has just a single clutch. Moreover a shorter overall length is achieved without the need to enlarge the overall diameter. Because of the combination of two or more electric machines arranged in accordance with the invention, it is possible to replace the previously customary torque converter for automatic transmissions. One of the electric motors is connected or can be connected in a torque-transmitting manner to the engine power-output shaft, the other is connected or can be connected in a torque-transmitting manner to the transmission power-input shaft, and a single engageable clutch is disposed between the two shafts.
The first electric machine, which is connected or can be connected in a torque-transmitting manner to the engine power-output shaft, is preferably designed as a starter for starting the combustion engine. At least one but preferably both electric machines are preferably integrated into a circuit in such a way that they can be used as an electric motor or as a generator for generating current, depending on the driving situation of the motor vehicle. In the generator mode, the two electric machines can be driven by the mass of the motor vehicle when the motor vehicle is in motion in order to recover the energy. When the vehicle is stationary and the clutch is disengaged, the first electric machine can generate current as a generator because of the running combustion engine. Both electric machines can be used for so-called impulse starts when the motor vehicle is operating in stop-and-go conditions. The second electric machine can be used to drive the motor vehicle for longer periods with the combustion engine disengaged.
Advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.